Grade 7L Heavy Hex Nut
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Grade 7L Heavy Hex Nut

ASTM A194 Grade 7 heavy hex nuts are manufactured from alloy steel, quenched and tempered. The ASTM A194 specification covers carbon steel, alloy steel, and stainless steel nuts for bolts in high pressure or high temperature service. They are a common high strength nut used with stud bolts for high and low temperature service, such as B16 and L7. When low temperature requirements are specified for Grade 7 nuts, the Charpy test procedures and requirements as defined in Specification A320/A320M for Grade L7 will apply. An "L" is added to the grade marking of these nuts. Dimensional specifications are governed by ASME B18.2.2. Heavy hex nuts provide increased bearing surface area over finished nuts such as J995 Grade 5 nuts.

Governing StandardsGrade 7

ASTM A194 This specification covers a variety of carbon, alloy, and martensitic stainless steel nuts in the size range 1⁄4 through 4 in. and metric M6 through M100 nominal. It also covers austenitic stainless steel nuts in the size range 1⁄4 in. and M6 nominal and above. These nuts are intended for high-pressure or high temperature service, or both. Grade substitutions without the purchaser’s permission are not allowed.
ASME B18.2.2 Covers the complete general and dimensional data for the various types of inch series square and hex nuts, including machine screw nuts and coupling nuts.
ASME B1.1 UNC & UNF Class 2B Specifies the thread form, series, class, allowance, tolerance, and designation for unified screw threads.

Grade 7 Marking
Grade 7 Material Marking

Grade 7 Marking
Grade 7L Material Marking

Mechanical PropertiesGrade 7

Alloy Steel Per ASTM A194/A194M-16
Diameter Proof Load Stress Core Hardness
Min psi Rockwell
1/4" thru 4" 175,000 C24 to C35

Chemical PropertiesGrade 7

Per ASTM A194/A194M-16
Grade Carbon Manganese Phosphorus Sulfur (1) Silicon Chromium Molybdenum
% by weight % by weight % by weight % by weight % by weight % by weight % by weight
7 0.38-0.48 0.75-1.00 0.035 max 0.040 max 0.15-0.35 0.80-1.10 0.15-0.25
  1. 1. Because of the degree to which sulfur segregates, product analysis for sulfur over 0.060 % max is not technologically appropriate.

Dimensional SpecificationsGrade 7

Heavy hex nut dimensions
Per ASME B18.2.2-2015
Nominal Diameter UNC UN8 F G H
Width Across Flats Width Across Corners Thickness
Basic Max Min Max Min Basic Max Min
1/4 0.250 20   1/2 0.500 0.488 0.577 0.556 15/64 0.250 0.218
5/16 0.313 18   9/16 0.562 0.546 0.650 0.220 19/64 0.314 0.280
3/8 0.375 16   11/16 0.688 0.669 0.794 0.763 23/64 0.377 0.341
7/16 0.438 14   3/4 0.750 0.728 0.866 0.830 27/64 0.441 0.403
1/2 0.500 13   7/8 0.875 0.850 1.010 0.990 31/64 0.504 0.464
9/16 0.563 12   15/16 0.938 0.909 1.083 1.037 35/64 0.568 0.526
5/8 0.625 11   1 1/16 1.062 1.031 1.227 1.175 39/64 0.631 0.587
3/4 0.750 10   1 1/4 0.250 1.212 1.443 1.382 47/64 0.758 0.710
7/8 0.875 9   1 7/16 1.438 1.394 1.660 1.589 55/64 0.885 0.833
1 1.000 8   1 5/8 1.625 1.575 1.876 1.796 63/64 1.012 0.956
1 1/8 1.125 7 8 1 13/16 1.812 1.756 2.093 2.002 1 7/64 1.139 1.079
1 1/4 1.250 7 8 2 2.000 1.380 2.309 2.209 1 7/32 1.251 1.187
1 3/8 1.375 6 8 2 3/16 2.188 2.119 2.526 2.416 1 11/32 1.378 1.310
1 1/2 1.500 6 8 2 3/8 2.375 2.300 2.742 2.622 1 15/32 1.505 1.433
1 5/8 1.625 5 1/2 8 2 9/16 2.562 2.481 2.959 2.828 1 19/32 1.632 1.556
1 3/4 1.750 5 8 2 3/4 2.750 2.662 3.175 3.035 1 23/32 1.759 1.679
1 7/8 1.875 5 8 2 15/16 2.938 2.844 3.392 3.242 1 27/32 1.886 1.802
2 2.000 4 1/2 8 3 1/8 3.125 3.025 3.608 3.449 1 31/32 2.013 1.925
2 1/4 2.250 4 1/2 8 3 1/2 3.500 3.388 4.041 3.862 2 13/64 2.251 2.155
2 1/2 2.500 4 8 3 7/8 3.875 3.750 4.474 4.275 2 29/64 2.505 2.401
2 3/4 2.750 4 8 4 1/4 4.250 4.112 4.907 4.688 2 45/64 2.759 2.647
3 3.000 4 8 4 5/8 4.625 4.475 5.340 5.102 2 61/64 3.013 2.893
3 1/4 3.250 4 8 5 5.000 4.838 5.774 5.515 3 3/16 3.252 3.124
3 1/2 3.500 4 8 5 3/8 5.375 5.200 6.207 5.928 3 7/16 3.506 3.370
3 3/4 3.750 4 8 5 3/4 5.750 5.562 5.562 6.341 3 11/16 3.670 3.616
4 4.000 4 8 6 1/8 6.125 5.925 5.925 6.755 3 15/16 4.014 3.862
  1. All dimensions are in inches.
Grade 7L Heavy Hex Nut
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Diameter Thread Pitch Width Across Flats Height of Nut Item # Availability Price Quantity UOM
1/2 13 7/8 0.4844 NHG70500000-I In Stock $0.48571/EA EA
5/8 11 1 1/16 0.6094 NHG70620000-I In Stock $0.54454/EA EA
3/4 10 1 1/4 0.7344 NHG70750000-I In Stock $0.89239/EA EA
7/8 9 1 7/16 0.8594 NHG70870000-I In Stock $1.39876/EA EA
1 8 1 5/8 0.9844 NHG71000000-I In Stock $2.0897/EA EA
1 1/8 8 1 13/16 1.1094 NHG71120000-I In Stock $2.08405/EA EA
1 1/4 8 2 1.2188 NHG71250000-I In Stock $3.29677/EA EA
1 3/8 8 2 3/16 1.3438 NHG71370000-I In Stock $3.35221/EA EA
1 1/2 8 2 3/8 1.4688 NHG71500000-I In Stock $4.2778/EA EA
1 5/8 8 2 9/16 1.5938 NHG71620000-I In Stock $5.17393/EA EA
1 3/4 8 2 3/4 1.7187 NHG71750000-I In Stock $6.27017/EA EA
1 7/8 8 2 15/16 1.8437 NHG71870000-I In Stock $14.43538/EA EA
2 8 3 1/8 1.9687 NHG72000000-I In Stock $10.77109/EA EA
2 1/4 8 3 1/2 2.2031 NHG72250000-I In Stock $18.41863/EA EA
2 1/2 8 3 7/8 2.4531 NHG72500000-I In Stock $19.12172/EA EA